Some vehicles may exhibit one or more of the following: Spark knock complaints when the vehicle is under load, various single cylinder misfire, and surge in 4th gear (around 45 mph). Our technicians tell us that rerouting the coil and spark plug wires to minimize induction effects will commonly correct this condition. If wires must cross during the reroute procedure, they must cross at a 90 degree angle.

Insufficient fuel pressure may be caused by particulate contaminates or other type of substances by-passing the primary fuel pick-up screen and resulting in fuel pump failure. Our technicians recommended to replace entire fuel pump module assembly as two (2) filters, primary and secondary are included with the assembly.

The engine may exhibit excessively high oil pressure at cold start up. This may lead to distortion of the oil filter case. Inspect the oil filter case for any signs of distortion. If the case is distorted, Connect an oil pressure gauge to the engine and start the engine while observing the readings. If the pressure reads above 80 psi, replace the oil pump.

The fuse may blow repeatedly for the HVAC blower motor or the motor may stop working all together. Our technicians tell us that can often be repaired by replacing the blower motor switch with a revised switch and installing a wiring harness with a relay assembly.

The blower motor may operate erratically and the blower switch operation has a sticky or mushy feeling, the detents almost non existent. Our technicians tell us that the blower switch should be removed and inspected for overheating. This is common if the blower motor is frequently operated on high speed as the current flow through the switch tends to melt internal the components. Also carefully inspect all of the switch connector terminals for discoloration due to overheating and replace as required. A poor electrical contact at the connector will also cause the switch to overheat.

Leak detection pump failure can be caused by the internal diaphragm switch sticking, or in some cases, contamination from debris or carbon particles from vapor canister. If black carbon particles are present in the LDP, replace vapor canister in addition to LDP. The purge solenoid should also be checked for debris or carbon contamination and replaced as necessary. All evap system hoses are subject to cracking and splitting causing leaks, Inspect hoses carefully. In cases of contamination from carbon particles or debris, all hoses and tubes must be blown out with compressed air to remove contaminates.

On the 3.9L V6, 5.2L V8 and 5.9L V8 the Oil leaks commonly from the valve cover gaskets, intake manifold gaskets (front and rear), timing cover gaskets, distributor O-ring, and the rear main seal area. Using fluorescent engine oil dye can be helpful in determining the source(s) of the oil leak.

The AC/heater (HVAC) system may unexpectedly switch to the defrost mode when accelerating. This system is operated by engine vacuum and should be inspected for any vacuum leaks if this problem develops. There is also a revised vacuum check valve available to address this concern.

A surging or bucking during acceleration can be caused if the distributor is moved or mis-indexed. This is a result of the cam and crank position sensors being out of synchronization. Wear of the oil pump drive gear can cause similar symptoms because it allows excessive free play in the distributor drive. The distributor drive gear and bushing should be replaced if the rotor tip moves back-and-forth more than 3/16th of an inch when checking drive gear free play.